Requirements for the use of alternative energy or clean energy have increased due to the rapid increase in the use of fossil fuels, and, as a part of this trend, power generation and electricity storage using an electrochemical reaction are the most actively researched areas.
Currently, a typical example of an electrochemical device using the electrochemical energy may be a secondary battery and there is a trend that its usage area is expanding more and more. In recent years, demand for secondary batteries as an energy source has been significantly increased as technology development and demand with respect to portable devices, such as portable computers, mobile phones, and cameras, have increased. Among these secondary batteries, lithium secondary batteries having high energy density, i.e., high capacity, have been subjected to considerable research and have been commercialized and widely used.
In general, a secondary battery is composed of a positive electrode, a negative electrode, an electrolyte, and a separator, in which charge and discharge may be possible, because lithium ions, which are discharged from a positive electrode active material by first charging, may act to transfer energy while moving between both electrodes, for example, the lithium ions are intercalated into a negative electrode active material, such as carbon particles, and deintercalated during discharging. The electrodes each include a current collector and an active material layer, and a binder is generally used to increase adhesion between the active material and the current collector and adhesion between active material particles.
Typically, in order to further increase the adhesion, techniques of adding a separate additive to an electrode slurry or increasing a ratio of the binder have been introduced. However, in a case in which the additive is added or an amount of the binder is increased, since an amount of the active material particles is reduced, capacity may be reduced.
Thus, there is a need to develop an electrode in which the adhesion between the active material and the current collector and the adhesion between the active material particles may be secured while maintaining high capacity of the battery.